QAM Modulation Schemes Research Articles

Design of MIMO K-Best Detection Algorithm And Its FPGA Implementation

Based on the research of MIMO Detection Algorithms theory and implementation methods, here novel k-Best MIMO detection algorithm is presented. Proposed algorithm uses an estimate technique and parallel sort approaches, which reduces the computational difficulty, and adopts pipelined configuration in parallel to save computation time. This algorithm implemented on Xilinx virtex-6. Implementation of proposed k-best multiple input multiple output detection algorithm on Field Programmable Gate Array is a challenging task by considering area and power. Computational complexity and resource utilization of this algorithm is discussed by implementing it on Virtex Field Programmable Gate Array. Field Programmable Gate Array implementation attained a good trade-off between power and area compared to the previous designs. Because of pipelined design and sorting procedure it is well suited for FPGA implementation and achieved 2.8 Gbps throughput for 64QAM modulation scheme with 4x4 systems. The flexibility of the scheme permits the high performance detection with low power consumption.

Performance Analysis of Hybrid RF/FSO System Using BPSK-SIM and DPSK-SIM Over Gamma-Gamma Turbulence Channel With Pointing Errors for Smart City Applications

The flourishing technology in wireless communication-free space optics (FSO) offers lots of merits over radio frequency (RF) links due to its license free bandwidth, ease of installation, high security features, and viable cost for short distance communication. It’s high speed data rate and immunity against electromagnetic interference makes FSO the emerging technology of today. But, FSO is not always reliable especially during atmospheric conditions, such as fog, rain, mist, and snow. Hence, in account a new technique of hybrid FSO/RF, this includes advantages of both FSO and RF technologies. Through this paper intend to perform an extensive analysis of the error and misalignment effects encountered in line of sight communication. Pointing error and turbulence effects are the main drawback parameters for our analysis. For this purpose I have taken into consideration different modulation techniques-binary phase shift keying-subcarrier intensity modulation, differential phase shift keying-subcarrier intensity modulation communication system with reference to on–off keying (OOK) modulation. The novel expressions for outage probability and BER for both FSO and RF system are derived which uses Rician channel and 16QAM modulation scheme alongside hybrid FSO/RF system for weak, moderate, and strong turbulence regimes using Meijer-G function.

TESTBED IMPLEMENTATION OF ENERGY EFFICIENT MULTI ANTENNA SYSTEM AND ITS PERFORMANCE EVALUATION

With the recent development and requirement for high-speed wireless communications, the demand of energy has increased exponentially in order to support required quality of service (QoS). Multiple Input Multiple Output (MIMO) technique gaining more popularity in current communication network, since it provides advantages in terms of higher data rates and maximum capacity with the cost of more energy consumption. In this paper, QAM modulation scheme is analyzed as the best modulation scheme for the total energy required to transmit the given number of bits is reduced. A SDR testbed has been built to implement Almouti coded MIMO system using LABVIEW and Universal Software Radio Peripheral (USRP) platform. The analysis was then extended to evaluate the energy consumption of the system where it was observed that by minimizing the transmission power the energy requirement of the system gets reduced. Then the system efficiency in terms of transmit power was evaluated using USRP. It has been observed that by adjusting carrier frequency transmit power of the system gets reduced up to 25%.Finally the performance of the system is evaluated by demonstrating the effect of transmission distance, symbol rate, spectral efficiency and circuit power on energy consumption of the system using LABVIEW math script.

${W}$ -Band Direct-Modulation >20-Gb/s Transmit and Receive Building Blocks in 32-nm SOI CMOS

This paper presents Gb/s-speed circuit building blocks in 32-nm CMOS SOI, for a > 20-Gb/s Cartesian direct-modulation $W$ -band transmitter. Transmitter systems non-idealities and performance limitations are discussed, and circuit design techniques and analyses are presented. The transmitter employs two 2-b high-speed RF digital-to-analog converters driven in quadrature, 20-dB gain $W$ -band LO drivers, and 30-Gb/s high-speed digital retimers and deserializers, and is capable of supporting BPSK/PAM4/QPSK/16-QAM modulation schemes, at a saturated output power $P_{\mathrm{ sat}}$ of +4 dBm. A maximum data rate of 20 Gb/s was achieved when operating in QPSK mode, 4 Gb/s in 16-QAM mode, and 12 Gb/s in both BPSK and PAM4 modes. The chip occupies 1.40.8 mm2 and consumes 110 mW in BPSK/PAM4 modes and 220 mW in QPSK and 16-QAM modes, resulting in the state-of-the-art 9-, 11-, and 55-pJ/b peak efficiencies, respectively. A mixer-first wideband $W$ -band receiver that includes a passive mixer and a wideband transimpedance amplifier is also presented. Measurements of the receiver chip demonstrated its capability to downconvert and amplify highly complex modulated waveforms (> 256-QAM), and at high data rates, up to 60 Gb/s in 64-QAM, which proves the feasibility of building high dynamic-range mm-wave receivers with bandwidth greater than 30 GHz. The receiver chip was also built in 32-nm CMOS SOI, occupying a core area of 0.180.1 mm2

A Spectrum Efficient Spatial Polarized QAM Modulation Scheme for Physical Layer Security in Dual-Polarized Satellite Systems

A Spectrum Efficient Spatial Polarized QAM Modulation Scheme for Physical Layer Security in Dual-Polarized Satellite Systems

English

English

Design and tests of 21 km, 5 Gbps, 0.14 THz wireless communication system

A terahertz wireless communication system is designed. The 16QAM modulation scheme is used in baseband processing, and mixers are used for cascading frequency up and down-converting. Cascading power amplification technique is adopted with a solid-state power amplifier and a vacuum electronic device. Several watts power is emitted at 0.14 THz. An all solid-state receiver running in room temperature is used, whose equivalent noise temperature is 1100 K and receiving sensitivity is -57 dBm. A 21 km wireless communication testing is carried out between the Shuangliu district and the Xinjin county of Chengdu, by means of two Cassegrain antennas with 50 dBi gain each. A 5 Gbps single-channel transmission speed is measured with bit error rate below 10-6. For testing, two standard HD-SDI uncompressed video streams are successfully transmitted in real time simultaneously, with an effective speed of 1.485 Gbps for each one.

Benefits of sliceable photonic-based transponders in metro and long-haul networks

In this paper, we analyze benefits of photonic integration-based sliceable transponders (sliceable photonics) compared to discrete optics transponder-based solutions (CFP/CFP2--C form-factor pluggable) in metro and long-haul networks. The metrics considered for comparison include the number of transponders, bandwidth use and power utilization. We assumed an OTN-based network with QPSK and 16QAM modulation schemes for both the scenarios. We observed that sliceable photonics is much more advantageous than discrete transponder optics in both metro and long-haul networks. We also compared the effect of modulation schemes on the efficiency of the network by comparing QPSK and 16QAM in discrete transponder optics and show that 16QAM in discrete transponder optics makes the network more inefficient.

A fully integrated CMOS 60-GHz transceiver for IEEE802.11ad applications

A fully integrated 60-GHz transceiver for 802.11ad applications with superior performance in a 90-nm CMOS process versus prior arts is proposed and real based on a field-circuit co-design methodology. The reported transceiver monolithically integrates a receiver, transmitter, PLL(Phase-Locked Loop) synthesizer, and LO (Local Oscillator) path based on a sliding-IF architecture. The transceiver supports up to a 16QAM modulation scheme and a data rate of 6 Gbit/s per channel, with an EVM (Error Vector Magnitude) of lower than −20 dB. The receiver path achieves a configurable conversion gain of 36∼64 dB and a noise figure of 7.1 dB over 57∼64 GHz, while consuming only 177 mW of power. The transmitter achieves a conversion gain of roughly 26 dB, with an output P1dB of 8 dBm and a saturated output power of over 10 dBm, consuming 252 mW of power from a 1.2-V supply. The LO path is composed of a 24-GHz PLL, doubler, and a divider chain, as well as an LO distribution network. In closed-loop operation mode, the PLL exhibits an integrated phase error of 3.3° rms (from 100 kHz to 100 MHz) over prescribed frequency bands, and a total power dissipation of only 26 mW. All measured results are rigorously loyal to the simulation.

Iterative Channel Estimation for Higher Order Modulated STBC-OFDM Systems with Reduced Complexity

In this paper, a frequency domain Expectation-Maximization (EM)-based channel estimation algorithm for Space Time Block Coded-Orthogonal Frequency Division Multiplexing (STBC-OFDM) systems is investigated to support higher data rate applications in wireless communications. The computational complexity of the frequency domain EM-based channel estimation is increased when higher order constellations are used because of the ascending size of the search set space. Thus, a search set reduction algorithm is proposed to decrease the complexity without sacrificing the system performance. The performance results of the proposed algorithm is obtained in terms of Bit Error Rate (BER) and Mean Square Error (MSE) for 16QAM and 64QAM modulation schemes.

Performance analysis of MIMO over MIMO-LTE for MQAM considering Rayleigh fading distribution

LTE (Long Term Evolution) is a 3GPP (Third Generation Partnership Project) wireless standards which uses the standard OFDMA (Orthogonal Frequency Division Multiple Access) modulation, MU-MIMO (Multiuser Multiple Input Multiple Output) technology and different multipath fading models. LTE allows the operator to use spectrum more efficiently to deliver high speed data. This paper characterizes the downlink performance of LTE. The requirement for high data rate applications demanded a system to provide users with the MIMO technology which constitutes a breakthrough in wireless communication and is defined in the LTE standard. There are many metric to characterize the performance, but one of the most convenient and informative metric is the BER (Bit Error Rate). So the performance is characterized in terms of BER. In this paper the LTE system is modeled and simulated using MATLAB and the BER for 2×2 and 4×4 MIMO-LTE using 16QAM and 64QAM modulation schemes for Rayleigh fading environment are obtained against different SNR values.

Ordered Successive Interference Cancellation for Maximum Throughput in Multi Stream MIMO using different Modulation Schemes

Objective: In this article performance evaluation of Multi Input Multi Output (MIMO) system using Alamouti and Spatial multiplexing with different modulation schemes is studied and in case of multi stream MIMO interference is suppressed by means of interference cancellation. Methods: In communication systems without any additional bandwidth MIMO offer considerable increase in data throughput and link range. In this paper performance of MIMO with Almouti code and spatial multiplexing is evaluated by means of BER (Bit Error Rate) performance under PSK and QAM modulation schemes. Findings: In this paper Minimum Mean Square Equalizer (MMSE) and Zero Force (ZF) equalizers are used for the estimation of received symbols. Estimates of MMSE and ZF are used for the Successive Interference Cancellation (SIC). In this article based on the received signal power an ordered successive interference cancellation is developed for maximum throughput. Improvements: The developed OSIC is tested with different modulation schemes and the performance are figured out for both SIC and OSIC.

Low complexity and area efficient reconfigurable multimode interleaver address generator for multistandard radios

Developing a reconfigurable transceiver to support multiple protocols seamlessly and efficiently is an extremely tough task. Wireless standards such as wireless local area network (IEEE 802.11a/g) and WiMAX (IEEE 802.16e) incorporate block interleaving technique to overcome the occurrence of burst errors during transmission. Field Programmable Gate Array (FPGA) implementation of floor and modulus (MOD) functions to perform the two step permutation for attaining the new index is quite complex. In this study, the authors propose a low complexity and area efficient reconfigurable architecture for multimode interleaver address generator to support multiple wireless standards. In addition, a novel MOD_row and MOD_column circuit are proposed to compute MOD function for row and column counter values, respectively. The proposed address generation circuitry supports BPSK, QPSK, 16-QAM and 64-QAM modulation schemes under all possible code rates. The reconfigurable address generator for various block size and modulation scheme are implemented on Xilinx Spartan XC3S400 FPGA and the functionalities are verified through simulation. The synthesis results of the proposed design shows a reduction of 60% in resource utilisation and an improvement of 46% in operating frequency over the existing approaches.

3.2 Gbps Channel-Adaptive Configurable MIMO Detector for Multi-Mode Wireless Communication

A configurable, channel-adaptive K-best MIMO detector for multi-mode wireless communications that adapts computation to varying channel conditions to achieve high energy-efficiency is presented. An 8-stage configurable MIMO detector supporting up to a 4×4 MIMO array and BPSK to 16-QAM modulation schemes has been implemented and simulated in 0.80V, 22nm Tri-gate CMOS process. Dynamic clock gating and power gating enable on-the-fly configuration and adaptive tuning of search radius K to channel response which results in 10% to 51% energy-efficiency improvement over non-adaptive K-best MIMO detectors. During unfavorable channel conditions, the MIMO detector satisfies target BER by setting K=5. For favorable channel conditions, K is reduced to 1, where 22nm circuit simulations show 68% energy reduction. At 1.0GHz target frequency, the total power consumption is 15mW (K=1) to 35mW (K=5), resulting in energy-efficiency of 14.2pJ/bit (K=1) to 44.7pJ/bit (K=5) and 3.2Gbps throughput.

A Design Approach for Two Stages GaN MMIC PAs With High Efficiency and Excellent Linearity

A novel design methodology for two stages microwave monolithic integrated circuit (MMIC) power amplifier (PA) is presented. The proposed solution allows to almost null the phase distortions (AM/PM) without worsening other key features of the PA, such as amplitude distortion (AM/AM) and efficiency. The derived approach is verified presenting the design and the experimental characterization of a two stages GaN MMIC PA for Microwave Backhaul radio links. The MMIC has been developed in a commercial 0.25 μm GaN power process, resulting in a 3×3 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> chip area. At 7 GHz, the realized module shows 6 W of saturated output power, 17 dB of gain, 63% of power added efficiency and less than 1.5 degree of phase distortion. Moreover, when tested with modulated signals (i.e., 256 QAM modulation scheme, 7 dB of PAPR), the PA shows a spectral regrow lower than -40 dBc at 32 dBm of average output power without any predistortion, while the average efficiency is around 30%.

Adaptive modulation and intra-symbol frequency-domain averaging scheme for multiband OFDM UWB over fiber system

To overcome the unbalanced error bit distribution among subcarriers caused by inter-subcarriers mixing interference (ISMI) and frequency selective fading (FSF), an adaptive modulation scheme based on 64/16/4QAM modulation is proposed and experimentally investigated in the intensity-modulation direct-detection (IM/DD) multiband orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) over fiber system. After 50km standard single mode fiber (SSMF) transmission, at the bit error ratio (BER) of 1×10−3, the experimental results show that the power penalty of the IM/DD MB-OFDM UWBoF system with 64/16/4QAM adaptive modulation scheme is about 3.6dB, compared to that with the 64QAM modulation scheme. Moreover, the receiver sensitivity has been improved about 0.52dB when the intra-symbol frequency-domain averaging (ISFA) algorithm is employed in the IM/DD MB-OFDM UWBoF system based on the 64/16/4QAM adaptive modulation scheme. Meanwhile, after 50km SSMF transmission, there is a negligible power penalty in the adaptively modulated IM/DD MB-OFDM UWBoF system, compared to the optical back-to-back case.

Design, comparative study and analysis of CDMA for different modulation techniques

In this work, we have design a MIMO–CDMA using 4∗8 antennas with the combination of MMSE (Minimum Mean square Error Equalizer) for BPSK (Binary Phase shift Keying), QPSK (Quadrature Phase Shift Keying), 16-QAM, 64-QAM and 256-QAM (Quadrature Amplitude Modulation) modulation schemes. The analysis is built on the basis of transmit–received signal, constellation and MMSE plot simulated on a MatLab/Simulink. On the basis of BER (Bit-Error-Rate), it is also concluded that this work is mostly suitable for high order modulation schemes as the BER of 16-qam, 64-QAM and 256-QAM is zero. The proposed study has increased the quality of the wireless link and Inter-Symbol-Interference (ISI) is likewise cut by applying a combination of MMSE and MIMO (Multiple In and Multiple Out) with OSTBC (Orthogonal space Time Block Code) encoder and combiner.

Going beyond 4 Gbps data rate by employing RGB laser diodes for visible light communication.

With increasing interest in visible light communication, the laser diode (LD) provides an attractive alternative, with higher efficiency, shorter linewidth and larger bandwidth for high-speed visible light communication (VLC). Previously, more than 3 Gbps data rate was demonstrated using LED. By using LDs and spectral-efficient orthogonal frequency division multiplexing encoding scheme, significantly higher data rates has been achieved in this work. Using 16-QAM modulation scheme, in conjunction with red, blue and green LDs, data rates of 4.4 Gbps, 4 Gbps and 4 Gbps, with the corresponding BER/SNR/EVM of 3.3 × 10⁻³/15.3/17.9, 1.4 × 10⁻³/16.3/15.4 and 2.8 × 10⁻³/15.5/16.7were obtained over transmission distance of ~20 cm. We also simultaneously demonstrated white light emission using red, blue and green LDs, after passing through a commercially available diffuser element. Our work highlighted that a tradeoff exists in operating the blue LDs at optimum bias condition while maintaining good color temperature. The best results were obtained when encoding red LDs which gave both the strongest received signal amplitude and white light with CCT value of 5835K.

Performance Analysis of Different Wavelet Families Over Fading Environments for Mobile WiMAX System

Orthogonal Frequency Division Multiplexing (OFDM) has made tremendous improvement possible in wireless technology. Wavelet analysis is used as an alternative to Fourier analysis in OFDM system to transform and map data onto orthogonal subcarriers, as it is a time-frequency domain operation thus it offers the advantages of optimal flexibility with less complexity. This paper presents performance analysis in terms of Bit Error rate (BER) of different wavelet families in OFDM System under the joint effect of path loss, multipath fading and noisy environment for Mobile WiMAX. The results obtained show that the performance of the mobile-multipath environments for 16QAM modulation schemes is enhanced as Daubechies and Biorthogonal wavelet families offers lower BER with different Path loss model. The performance measurements and analysis was done in simulation developed in MATLAB.

English

A detail analysis of the performance of 2X2 MIMO (Multiple Input Multiple Output) antenna systems has been carried out for three different types of detectors at the receiver end by determining the transmit diversity using OSTBC multiplexing techniques. The transmission characteristics of the MIMO system have been determined for BPSK, QPSK and 16-QAM modulation schemes presuming Additive White Gaussian Noise (AWGN) and for the flat fading Rayleigh channel. On the receiver side, equalization detection technique are determined by combining Successive Interference Cancellation with Zero Forcing (ZF-SIC), Minimum Mean Square Equalization (MMSE-SIC) and Maximum Likelihood (ML-SIC) has been employed for determining the BER Vs SNR performance of the communication channel. The simulation results show that for BER of ~10-3, the SNR increases with higher modulation schemes from BPSK to 16-QAM. Further the results of the analysis for different detector systems indicate that for BPSK modulation at BER ~10-3 , the SNR values are found to be ~24.46 dB for ZF-SIC, SNR ~20.6 dB for MMSESIC and SNR ~14.46 dB for ML-SIC detectors. Thus the BER performance of 2X2 MIMO-OSTBC transmission channel shows the reduction of SNR ~10 dB for ML detectors. A comparison of the MIMO performance with OSTBC multiplexing techniques indicate that the 2x2 MIMO–OSTBC transmission channel for BPSK modulation depicts better performance for OSTBC multiplexing with ML detector system at the receiving end. The simulations results are presented and discussed in the paper.